DE 10 2008 048 228 A9 discloses a fuel filter having a fuel filter insert including a pre-filter element and a main filter element which are situated one after the other in the axial direction to the longitudinal axis of the fuel filter. The fuel pre-filtered by the pre-filter element is pumped to the main filter element by way of a fuel pump situated outside of the filter housing.
A fluid filter having a filter housing is known from U.S. Pat. No. 3,900,400 B, in which two filter elements are arranged one above the other in the direction of the longitudinal axis of the fluid filter and which can be exchanged independent from each other. An inlet channel is formed for the fluid between the two filter elements, which is axially limited by a lower end plate of the two filter elements and by a housing clamping plate spring elastically braced at the end plate. By means of the housing clamping plate, the upper filter element of the two filter elements sealingly abuts at the housing cover of the filter housing.
EP 0 852 158 A1 shows a fuel filter having two fluidically connected filter elements situated one after the other which, in the direction of the longitudinal axis of the fuel filter, are situated one above the other.
WO 2006/070221 A1 shows a further fuel filter having a pre- and main filter element which are situated in a concentric manner to the longitudinal axis of the fuel filter.
Similar fuel filters are known from DE 20 2006 004 527 U1 and EP 1 485 605 B1.